This invention relates to a rotor for a disc brake assembly, and more specifically, the invention relates to a servoing disc brake rotor.
Servo-type rotor assemblies have been used for various brake applications. Servo rotors typically include a pair of annular members spaced apart from one another. The surfaces of the annular members that face one another include ramped pockets that receive a plurality of balls therebetween. When one of the members is rotated relative to the other member, the balls and ramps cause the members to move away from one another. That is, as the members are rotated relative to one another, the rotor assembly becomes wider.
Such rotor assemblies have been used as brake adjusters in brake actuators. As the friction members wear in the brake assembly the servo rotor members are rotated relative to one another to take up clearance in the brake assembly due to wear. The servo rotors for these applications do not create any braking force.
Servo rotors assemblies have also been used to apply a braking force to rotating members in a vehicle. An annular housing having a U-shaped cross-section is attached to a rotating member such as a vehicle wheel or clutch. The servo rotor is disposed within the housing. Outer surfaces of the annular rotor members have friction linings adjacent to the housing. At least one hydraulic actuator interconnects the arcuate members for moving the members rotationally relative to one another. The friction lining on the members engage the housing to apply a braking force and slow the rotating member. The servo rotors for these applications have been the only braking force and have not been used to supplement conventional braking mechanisms.
For conventional disc brake assemblies a particular brake input force will provide a particular brake torque. It is desirable to increase the brake torque without increasing the brake input force. However, providing additional brake torque has required either additional braking mechanisms that have additional actuators or more robust brake components that can provide the higher brake input force. Therefore, what is needed is a passive brake component that is capable of providing a supplemental brake clamping force to current brake input forces and provide an increased brake torque.
The present invention provides a self-servoing disc brake assembly that includes a driven rotor member having a first inner surface with a plurality of first pockets. The driven rotor member also includes a first friction surface spaced from the first inner surface. A movable rotor member is supported on the driven rotor member and is movable relative to the driven rotor member between non-servoed and servoed positions. The friction surfaces are spaced a first distance in the non-servo position, and the friction surfaces are spaced a second distance which is greater than a first distance in the servo position. The movable rotor member includes a second inner surface with a plurality of second pockets adjacent to the first inner surface and a friction surface spaced from the second inner surface. A plurality of balls are arranged between the first and second pockets with at least one of the first and second pockets being ramped. A friction member, such as a disc brake pad, is arranged adjacent to the first friction surface and is movable between engaged and non-engaged positions. The friction member is spaced from the second friction surface in the non-engaged position and the friction member is in contact with the second friction surface in the engaged position to rotate the movable rotor member to the servoed position and produce a supplemental brake clamping force. As the brake pads are moved into engagement with the driven and movable rotor members, a shear force is created on the second friction surface. The shear force causes the movable rotor member to rotate relative to and away from the driven rotor member. As a result, for a particular brake input force a larger braking torque is achieved.
Accordingly, the above invention provides a passive brake component that is capable of providing a supplemental brake clamping force to current brake input forces to provide an increased brake torque.